In the related art, a driving assistance device is known, which includes means for imaging that can image a rear side area of a vehicle and a blind area such as an area outside of a visible range of a side mirror adjacent to the rear side area, and means for displaying that displays the image imaged by the means for imaging such that the imaged image can be visible to a driver. By enlarging the area within the visible range of the side mirror and compressing the blind area outside of the visible range of the side mirror, the driving assistance device eliminates discomfort to the driver when viewing the door mirror and a monitor, and makes the perception of distance with respect to another vehicle when viewing the another vehicle by the door mirror coincident with that by the monitor.